Rationalization of the softening and recrystallization behaviour of microalloyed austenite using mechanism maps

Zurob, Hatem S.; Hutchinson, Christopher; Bréchet, Y.; Purdy, G.R.

doi:10.1016/j.msea.2004.04.024

Cited by 40 publications

(28 citation statements)

References 31 publications

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“…This clearly showed that precipitation is the more effective means of retarding recrystallization. The same conclusion was reached based on the physically-based model of Zurob et al 4,17,18) Thus the phenomenological observations in the present work on high Nb steel with different Mn levels warrant more in-depth analysis to sort out the relative contributions of solute and strain-induced precipitation to the retardation of recovery and recrystallization kinetics. …”

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confidence: 85%

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Analysis of the Effect of Mn on the Recrystallization Kinetics of High Nb Steel: An Example of Physically-based Alloy Design

Zurob¹,

Zhu

Subramanian

et al. 2005

ISIJ Int.

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Strip casting and thin slab casting are new near net-shape technologies, which have successfully emerged in steels because of significant energy savings, substantial reduction in green house gas emissions and cost benefits. Extensive research was undertaken aimed at integrating microalloying technology with near net-shape casting technology, using a base chemistry of low carbon (0.03 wt%) and high niobium (up to 0.1%wt), which is a well established chemistry for higher grade pipeline steels.In the present contribution, physically-based modelling is used to optimize the Mn content and the processing conditions for the application of strain-accumulation in the new steels. The results of the modelling confirm the distinct advantage of the low Mn chemistry for the application of plate rolling which is carried out in the high temperature window using small to medium deformation passes. The high Mn chemistry is found to be more advantageous when the rolling is carried out in the low temperature window and using large pass reductions. This result is in agreement with recent rolling simulations and mill trials which show that the high Mn chemistry is superior to the low Mn chemistry for the application of near net-shape strip-rolling.KEY WORDS: strip-rolling; effect of Mn; recrystallization; recovery; precipitation; solute-drag; process optimization.The predictive capability of the physically-based approach makes it possible to explore material behaviour over short interpass times which are difficult to access experimentally. We are thus able to optimize, to a first order, the steel chemistry and processing conditions for the strip-rolling of high Nb steels. Further optimization of the chemistry and processing conditions requires experimental inputs that would allow for the verification and improvement of the model. Thus, an important theme of the present contribution is the need to use physically-based modelling in parallel with carefully designed experiments.We start by reviewing the existing experimental observations on the effect of Mn on precipitation and recrystallization (Sec. 2). We then present a physically-based model for the microstructural evolution of hot-rolled austenite during the interpass time (Sec. 3). In Sec. 4, the model is used to analyze the effect of Mn content on the softening kinetics for various processing conditions (i.e. various combinations of temperature and strain). The industrial implications of the model are considered in Sec. 5. Table 1 identifies the base chemistry of the steels being investigated for the application of strain-accumulation in the low temperature window. As mentioned earlier, the low carbon design is based on the need to achieve a very homogenous solid-state microstructure even with high alloying addition of substitutional solutes like Mn and Nb. The contents of N and Ti are based on quantitative modelling of the thermodynamic potential for the precipitation of Ti-Nb carbo-nitrides. These models 5,6) show a distinct advantage of low nitrogen (0.003 wt%) design. The tita...

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confidence: 85%

“…[17][18][19] This appendix summarizes the model parameters which are necessary to reproduce the results of Figs. 6, 7 and 8.…”

Section: Appendix (1) Values Of the Parameters Used In The Modelmentioning

confidence: 99%

Analysis of the Effect of Mn on the Recrystallization Kinetics of High Nb Steel: An Example of Physically-based Alloy Design

Zurob¹,

Zhu

Subramanian

et al. 2005

ISIJ Int.

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“…On the one hand, Zurob et al [36] suggest that dislocation pinning by precipitates represents the origin of the measured plateaus. These authors argue that static recovery is severely hindered if the number density of precipitates exerts a certain limit.…”

Section: Resultsmentioning

confidence: 96%

A Model for Static Recrystallization with Simultaneous Precipitation and Solute Drag

Buken

Kozeschnik

2016

Metall Mater Trans A

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In the present work, we introduce a state parameter-based microstructure evolution model, which incorporates the effect of solute atoms and precipitates on recrystallization kinetics. The model accounts for local precipitate coarsening at grain boundaries, which promotes an average grain boundary movement even if the Zener pinning force exceeds the driving force for recrystallization. The impact of solute drag on the grain boundary mobility as well as simultaneous precipitation is discussed in detail. The model is validated on experimental data on recrystallization in V-micro-alloyed steel, where excellent agreement is achieved.

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“…As in previous studies, [6,7,20] we have used the flow stress of the as-rolled material in order to estimate the driving force for recrystallization. The hardness of the as-rolled diffusion couple was measured at many points throughout the sample and found to be constant.…”

Section: A Recrystallizationmentioning

confidence: 99%

“…The effect of precipitates on recrystallization, from the perspective of alloy design, has been investigated recently in microalloyed steels. [6,7,8] The role of Nb in solid solution, on the other hand, is more subtle and is the topic of the present investigation.…”

Section: Introductionmentioning

confidence: 97%

The Effect of Nb on the Recrystallization and Grain Growth of Ultra-High-Purity α-Fe: A Combinatorial Approach

Sinclair

Hutchinson

Bréchet³

2007

Metall Mater Trans A

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A combinatorial approach to the problem of the effect of Nb in solid solution on the conditions for recrystallization and grain growth in ultra-high-purity (UHP) a-Fe is presented. It is shown to be an efficient means for estimating parameters such as the binding energy of solute to grain boundaries, the transboundary solute diffusivity, and the intrinsic mobility of grain boundaries, crucial for practical applications of existing solute drag theories to questions related to alloy design. Using a Fe-Nb diffusion couple (Nb contents ranging from 0 to 0.095 wt pct) transformed within a temperature gradient (RT-850°C), the boundary between the recrystallized and unrecrystallized regions and the grain growth behavior as a function of Nb content and temperature could be quantitatively rationalized using the slow branch of Cahn's solution to the solute drag problem.

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Rationalization of the softening and recrystallization behaviour of microalloyed austenite using mechanism maps

Cited by 40 publications

References 31 publications

Analysis of the Effect of Mn on the Recrystallization Kinetics of High Nb Steel: An Example of Physically-based Alloy Design

Analysis of the Effect of Mn on the Recrystallization Kinetics of High Nb Steel: An Example of Physically-based Alloy Design

A Model for Static Recrystallization with Simultaneous Precipitation and Solute Drag

The Effect of Nb on the Recrystallization and Grain Growth of Ultra-High-Purity α-Fe: A Combinatorial Approach

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